(function(){
    if (typeof self === 'undefined' || !self.Prism || !self.document) {
        return;
    }

    var callbacks = [];
    var map = {};
    var noop = function() {};

    Prism.plugins.toolbar = {};

    /**
     * Register a button callback with the toolbar.
     *
     * @param {string} key
     * @param {Object|Function} opts
     */
    var registerButton = Prism.plugins.toolbar.registerButton = function (key, opts) {
        var callback;

        if (typeof opts === 'function') {
            callback = opts;
        } else {
            callback = function (env) {
                var element;

                if (typeof opts.onClick === 'function') {
                    element = document.createElement('button');
                    element.type = 'button';
                    element.addEventListener('click', function () {
                        opts.onClick.call(this, env);
                    });
                } else if (typeof opts.url === 'string') {
                    element = document.createElement('a');
                    element.href = opts.url;
                } else {
                    element = document.createElement('span');
                }

                element.textContent = opts.text;

                return element;
            };
        }

        callbacks.push(map[key] = callback);
    };

    /**
     * Post-highlight Prism hook callback.
     *
     * @param env
     */
    var hook = Prism.plugins.toolbar.hook = function (env) {
        // Check if inline or actual code block (credit to line-numbers plugin)
        var pre = env.element.parentNode;
        if (!pre || !/pre/i.test(pre.nodeName)) {
            return;
        }

        // Autoloader rehighlights, so only do this once.
        if (pre.parentNode.classList.contains('code-toolbar')) {
            return;
        }

        // Create wrapper for <pre> to prevent scrolling toolbar with content
        var wrapper = document.createElement("div");
        wrapper.classList.add("code-toolbar");
        pre.parentNode.insertBefore(wrapper, pre);
        wrapper.appendChild(pre);

        // Setup the toolbar
        var toolbar = document.createElement('div');
        toolbar.classList.add('toolbar');

        if (document.body.hasAttribute('data-toolbar-order')) {
            callbacks = document.body.getAttribute('data-toolbar-order').split(',').map(function(key) {
                return map[key] || noop;
            });
        }

        callbacks.forEach(function(callback) {
            var element = callback(env);

            if (!element) {
                return;
            }

            var item = document.createElement('div');
            item.classList.add('toolbar-item');

            item.appendChild(element);
            toolbar.appendChild(item);
        });

        // Add our toolbar to the currently created wrapper of <pre> tag
        wrapper.appendChild(toolbar);
    };

    registerButton('label', function(env) {
        var pre = env.element.parentNode;
        if (!pre || !/pre/i.test(pre.nodeName)) {
            return;
        }

        if (!pre.hasAttribute('data-label')) {
            return;
        }

        var element, template;
        var text = pre.getAttribute('data-label');
        try {
            // Any normal text will blow up this selector.
            template = document.querySelector('template#' + text);
        } catch (e) {}

        if (template) {
            element = template.content;
        } else {
            if (pre.hasAttribute('data-url')) {
                element = document.createElement('a');
                element.href = pre.getAttribute('data-url');
            } else {
                element = document.createElement('span');
            }

            element.textContent = text;
        }

        return element;
    });

    /**
     * Register the toolbar with Prism.
     */
    Prism.hooks.add('complete', hook);
})();